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Mineral speciesFormula
 ForsteriteMg2SiO4 
Mineralogy
Family: Olivine Group 
Space group: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pbnm 
Dana class: 51.3.1.2 (51) Nesosilicate Insular SiO4 Groups Only (51.3) with all cations in octahedral [6] coordination (51.3.1)Olivine group 
Geological context
High temperature: Medium to high temperature mineral, 650C C is a temperature estimated from a deposit. 
Geological context: Same as fluorphlogopite, occurs commonly in metamorphic environment associated with marble. 
Thermodynamics
Individual properties
Molar weight: 140.693 g/mol  ΔGºf-2,056,704 J/mol ref.  Sº: 95.19 J/mol/K ref. 
  ΔHºf-2,175,746 J/mol ref.  Cp: 117.89 J/mol/K ref. 
Reaction properties
Chemical reaction:  Forsterite + 4H+ = 2Mg+2 + H4SiO4 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -7.39423905e+2   -1.11954345e-1   4.97152038e+4   2.65827089e+2   -2.05434932e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)28.60
ΔH°r-219,449 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  32.13   28.60   24.59   20.96   17.41   14.59   12.22   10.12 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:149.83 J/mol/K 
b:27.36 J/mol/K2 
c:-35.65 J.K/mol 

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